Research activity information

• Jul. 2023 一般財団法人 敬愛まちづくり財団, 前之園記念若手優秀論文賞


• Nov. 2022 The Eicosanoid Research Foundation, ERF Young Investigator Award, Molecular basis of unique specificity and ATP activation of group VIA calcium-independent phospholipase A2

  Daiki Hayashi


• Jan. 2020 公益財団法人 上原記念生命科学財団, ポストドクトラルフェローシップ, 脂質加水分解酵素PLA2の基質特異性の包括的解明

• Next generation thiazolyl ketone inhibitors of cytosolic phospholipase A2 α for targeted cancer therapy.

  Felicity J Ashcroft, Asimina Bourboula, Nur Mahammad, Efrosini Barbayianni, Astrid J Feuerherm, Thanh Thuy Nguyen, Daiki Hayashi, Maroula G Kokotou, Konstantinos Alevizopoulos, Edward A Dennis, George Kokotos, Berit Johansen

  Eicosanoids are key players in inflammatory diseases and cancer. Targeting their production by inhibiting Group IVA cytosolic phospholipase A2 (cPLA2α) offers a promising approach for cancer therapy. In this study, we synthesize a second generation of thiazolyl ketone inhibitors of cPLA2α starting with compound GK470 (AVX235) and test their in vitro and cellular activities. We identify a more potent and selective lead molecule, GK420 (AVX420), which we test in parallel with AVX235 and a structurally unrelated compound, AVX002 for inhibition of cell viability across a panel of cancer cell lines. From this, we show that activity of polycomb group repressive complex 2 is a key molecular determinant of sensitivity to cPLA2α inhibition, while resistance depends on antioxidant response pathways. Consistent with these results, we show that elevated intracellular reactive oxygen species and activating transcription factor 4 target gene expression precede cell death in AVX420-sensitive T-cell acute lymphoblastic leukemia cells. Our findings imply cPLA2α may support cancer by mitigating oxidative stress and inhibiting tumor suppressor expression and suggest that AVX420 has potential for treating acute leukemias and other cancers that are susceptible to oxidative cell death.

  Jan. 2025, Nature communications, 16(1) (1), 164 - 164, English, International magazine

  [Refereed]

  Scientific journal


• The mechanism of allosteric regulation of calcium-independent phospholipase A2 by ATP and calmodulin binding to the ankyrin domain.

  Varnavas D Mouchlis, Yuan-Hao Hsu, Daiki Hayashi, Jian Cao, Sheng Li, J Andrew McCammon, Edward A Dennis

  Group VIA calcium-independent phospholipase A2 (iPLA2) is a member of the PLA2 superfamily that exhibits calcium-independent activity in contrast to the other two major types, secreted phospholipase A2 (sPLA2) and cytosolic phospholipase A2 (cPLA2), which both require calcium for their enzymatic activity. Adenosine triphosphate (ATP) has been reported to allosterically activate iPLA2, and this has now been verified with a lipidomics-based mixed-micelle assay, but its mechanism of action has been unknown. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) was employed to identify ATP interaction peptide regions located within the ankyrin repeat domain at which ATP interacts. Molecular dynamics simulations revealed the mechanism by which ATP binds to its site and the main residues that interact. Site-directed mutagenesis was used to verify the importance of these residues in the role of ATP in regulating iPLA2 activity. Importantly, calcium was found to abolish the enhancing regulatory function of ATP and to promote the inhibitory activity by calmodulin. Given previous evidence that calcium does not bind directly to iPLA2, its effect appears to be indirect via association with ATP and/or calmodulin. Using HDX-MS, we found that calmodulin interacts with the N terminus peptide region of iPLA2 consisting of residues 20 to 28. These two regulatory iPLA2 sites open the road to the development of potential targets for therapeutic intervention.

  Nov. 2024, Proceedings of the National Academy of Sciences of the United States of America, 121(48) (48), e2411539121, English, International magazine

  [Refereed]

  Scientific journal


• Differentiating human phospholipase A2's activity toward phosphatidylinositol, phosphatidylinositol phosphate and phosphatidylinositol bisphosphate.

  Daiki Hayashi, Edward A Dennis

  Phospholipase A2's (PLA2's) constitute a superfamily of enzymes that hydrolyze the sn-2 fatty acyl chain on glycerophospholipids. We have previously reported that each PLA2 Type shows a unique substrate specificity for the molecular species it hydrolyzes, especially the acyl chain that is cleaved from the sn-2 position and to some extent the polar group. However, phosphatidylinositol (PI) and PI phosphates (PIPs) have not been as well studied as substrates as other phospholipids because the PIPs require adaptation of the standard analysis methods, but they are important in vivo. We determined the in vitro activity of the three major types of human PLA2's, namely the cytosolic (c), calcium-independent (i), and secreted (s) PLA2's toward PI, PI-4-phosphate (PI(4)P), and PI-4,5-bisphosphate (PI(4,5)P2). The in vitro assay revealed that Group IVA cPLA2 (GIVA cPLA2) showed relatively high activity toward PI and PI(4)P among the tested PLA2's; nevertheless, the highly hydrophilic headgroup disrupted the interaction between the lipid surface and the enzyme. GIVA cPLA2 and GVIA iPLA2 showed detectable activity toward PI(4,5)P2, but it appeared to be a poorer substrate for all of the PLA2's tested. Furthermore, molecular dynamics (MD) simulations demonstrated that Thr416 and Glu418 of GIVA cPLA2 contribute significantly to accommodating the hydrophilic head groups of PI and PI(4)P, which could explain some selectivity for PI and PI(4)P. These results indicated that GIVA cPLA2 can accommodate PI and PI(4)P in its active site and hydrolyze them, suggesting that the GIVA cPLA2 may best account for the PI and PIP hydrolysis in living cells.

  Lead, Jun. 2024, Biochimica et Biophysica Acta. Molecular and Cell Biology of Lipids, 1869(7) (7), 159527 - 159527, English, International magazine

  [Refereed][Invited]

  Scientific journal


• Molecular basis of unique specificity and regulation of group VIA calcium-independent phospholipase A2 (PNPLA9) and its role in neurodegenerative diseases.

  Daiki Hayashi, Edward A Dennis

  Glycerophospholipids are major components of cell membranes and consist of a glycerol backbone esterified with one of over 30 unique fatty acids at each of the sn-1 and sn-2 positions. In addition, in some human cells and tissues as much as 20% of the glycerophospholipids contain a fatty alcohol rather than an ester in the sn-1 position, although it can also occur in the sn-2 position. The sn-3 position of the glycerol backbone contains a phosphodiester bond linked to one of more than 10 unique polar head-groups. Hence, humans contain thousands of unique individual molecular species of phospholipids given the heterogeneity of the sn-1 and sn-2 linkage and carbon chains and the sn-3 polar groups. Phospholipase A2 (PLA2) is a superfamily of enzymes that hydrolyze the sn-2 fatty acyl chain resulting in lyso-phospholipids and free fatty acids that then undergo further metabolism. PLA2's play a critical role in lipid-mediated biological responses and membrane phospholipid remodeling. Among the PLA2 enzymes, the Group VIA calcium-independent PLA2 (GVIA iPLA2), also referred to as PNPLA9, is a fascinating enzyme with broad substrate specificity and it is implicated in a wide variety of diseases. Especially notable, the GVIA iPLA2 is implicated in the sequelae of several neurodegenerative diseases termed "phospholipase A2-associated neurodegeneration" (PLAN) diseases. Despite many reports on the physiological role of the GVIA iPLA2, the molecular basis of its enzymatic specificity was unclear. Recently, we employed state-of-the-art lipidomics and molecular dynamics techniques to elucidate the detailed molecular basis of its substrate specificity and regulation. In this review, we summarize the molecular basis of the enzymatic action of GVIA iPLA2 and provide a perspective on future therapeutic strategies for PLAN diseases targeting GVIA iPLA2.

  Mar. 2023, Pharmacology & therapeutics, 245, 108395 - 108395, English, International magazine

  [Refereed][Invited]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Vitamin E functions by association with a novel binding site on the 67 kDa laminin receptor activating diacylglycerol kinase

  Daiki Hayashi, Varnavas D. Mouchlis, Seika Okamoto, Tomoka Namba, Liuqing Wang, Sheng Li, Shuji Ueda, Minoru Yamanoue, Hirofumi Tachibana, Hiroyuki Arai, Hitoshi Ashida, Edward A. Dennis, Yasuhito Shirai

  It is generally recognized that the main function of α-tocopherol (αToc), which is the most active form of vitamin E, is its antioxidant effect, while non-antioxidant effects have also been reported. We previously found that αToc ameliorates diabetic nephropathy via diacylglycerol kinase alpha (DGKα) activation in vivo, and the activation was not related to the antioxidant effect. However, the underlying mechanism of how αToc activates DGKα have been enigmatic. We report that the membrane-bound 67 kDa laminin receptor (67LR), which has previously been shown to serve as a receptor for epigallocatechin gallate (EGCG), also contains a novel binding site for vitamin E, and its association with Vitamin E mediates DGKα activation by αToc. We employed hydrogen-deuterium exchange mass spectrometry (HDX/MS) and molecular dynamics (MD) simulations to identify the specific binding site of αToc on the 67LR and discovered the conformation of the specific hydrophobic pocket that accommodates αToc. Also, HDX/MS and MD simulations demonstrated the detailed binding of EGCG to a water-exposed hydrophilic site on 67LR, while in contrast αToc binds to a distinct hydrophobic site. We demonstrated that 67LR triggers an important signaling pathway mediating non-antioxidant effects of αToc, such as DGKα activation. This is the first evidence demonstrating a membrane receptor for αToc and one of the underlying mechanisms of a non-antioxidant function for αToc.

  Lead, Dec. 2022, The Journal of Nutritional Biochemistry, 110, 109129 - 109129, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• The Role of Diacylglycerol Kinase in the Amelioration of Diabetic Nephropathy

  Daiki Hayashi, Yasuhito Shirai

  The drastic increase in the number of patients with diabetes and its complications is a global issue. Diabetic nephropathy, the leading cause of chronic kidney disease, significantly affects patients' quality of life and medical expenses. Furthermore, there are limited drugs for treating diabetic nephropathy patients. Impaired lipid signaling, especially abnormal protein kinase C (PKC) activation by de novo-synthesized diacylglycerol (DG) under high blood glucose, is one of the causes of diabetic nephropathy. DG kinase (DGK) is an enzyme that phosphorylates DG and generates phosphatidic acid, i.e., DGK can inhibit PKC activation under diabetic conditions. Indeed, it has been proven that DGK activation ameliorates diabetic nephropathy. In this review, we summarize the involvement of PKC and DGK in diabetic nephropathy as therapeutic targets, and its mechanisms, by referring to our recent study.

  Oct. 2022, Molecules, 27(20) (20), English, International magazine

  [Refereed][Invited]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• N-Acylated and N-Alkylated 2-Aminobenzothiazoles Are Novel Agents That Suppress the Generation of Prostaglandin E2.

  Maria A Theodoropoulou, Anastasia Psarra, Martin Erhardt, Aikaterini Nikolaou, Anna-Dimitra D Gerogiannopoulou, Dimitra Hadjipavlou-Litina, Daiki Hayashi, Edward A Dennis, Andrea Huwiler, George Kokotos

  The quest for novel agents to regulate the generation of prostaglandin E2 (PGE2) is of high importance because this eicosanoid is a key player in inflammatory diseases. We synthesized a series of N-acylated and N-alkylated 2-aminobenzothiazoles and related heterocycles (benzoxazoles and benzimidazoles) and evaluated their ability to suppress the cytokine-stimulated generation of PGE2 in rat mesangial cells. 2-Aminobenzothiazoles, either acylated by the 3-(naphthalen-2-yl)propanoyl moiety (GK510) or N-alkylated by a chain carrying a naphthalene (GK543) or a phenyl moiety (GK562) at a distance of three carbon atoms, stand out in inhibiting PGE2 generation, with EC50 values ranging from 118 nM to 177 nM. Both GK510 and GK543 exhibit in vivo anti-inflammatory activity greater than that of indomethacin. Thus, N-acylated or N-alkylated 2-aminobenzothiazoles are novel leads for the regulation of PGE2 formation.

  Feb. 2022, Biomolecules, 12(2) (2), English, International magazine

  [Refereed]

  Scientific journal


• Lipoprotein-associated phospholipase A 2 : A paradigm for allosteric regulation by membranes

  Varnavas D. Mouchlis, Daiki Hayashi, Alexis M. Vasquez, Jian Cao, J. Andrew McCammon, Edward A. Dennis

  Proceedings of the National Academy of Sciences, Jan. 2022, Proceedings of the National Academy of Sciences, 119(2) (2), English

  [Refereed]

  Scientific journal


• Each phospholipase A2 type exhibits distinct selectivity toward sn-1 ester, alkyl ether, and vinyl ether phospholipids

  Daiki Hayashi, Varnavas D. Mochlis, Edward A. Dennis

  Lead, Jan. 2022, Biochimica et Biophysica Acta (BBA)-Molecular and Cell Biology of Lipids, 1867(1) (1), English

  [Refereed]

  Scientific journal


• Omega-3 versus Omega-6 fatty acid availability is controlled by hydrophobic site geometries of phospholipase A2s

  Daiki Hayashi, Varnavas D. Mouchlis, Edward A. Dennis

  Lead, Elsevier {BV}, Aug. 2021, Journal of Lipid Research, 62, 100113 - 100113, English

  [Refereed]

  Scientific journal


• The mechanisms of ameliorating effect of a green tea polyphenol on diabetic nephropathy based on diacylglycerol kinase α

  Daiki Hayashi, Liuqing Wang, Shuji Ueda, Minoru Yamanoue, Hitoshi Ashida, Yasuhito Shirai

  AbstractSignificant efforts have been made to ameliorate diabetic nephropathy (DN) by inhibiting protein kinase C. However, these efforts have not been successful in human trials, suggesting that novel therapeutic strategies are required. Thus far, it has been reported that green tea polyphenol epigallocatechin gallate (EGCg) improved albuminuria in DN in a human trial. Our previous study revealed that activation of diacylglycerol kinase α (DGKα) plays a crucial role in the amelioration of DN and that EGCg activates DGKα. Here, we investigated whether and how DGKα contributes to the amelioration of DN upon stimulation by EGCg by using streptozotocin-induced type 1 diabetic model mice. Our results revealed that EGCg ameliorated albuminuria in DN through DGKα in vivo, and methylated EGCg, which has higher absorption in the plasma improved albuminuria in DN effectively. Additionally, we showed that c-Src mediated EGCg-induced DGKα translocation and colocalized with the 67 kDa laminin receptor, which is an EGCg receptor. Furthermore, EGCg attenuated the loss of podocytes in DN by preventing a decrease in focal adhesion under high glucose conditions. Our results indicate that the DGKα pathway is an attractive therapeutic target and that activating this pathway is a novel strategy for treating DN.

  Lead, Springer Science and Business Media {LLC}, Dec. 2020, Scientific Reports, 10(1) (1), English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• 2-Oxoester Phospholipase A2 Inhibitors with Enhanced Metabolic Stability

  Giorgos S. Koutoulogenis, Maroula G. Kokotou, Daiki Hayashi, Varnavas D. Mouchlis, Edward A. Dennis, George Kokotos

  2-Oxoesters constitute an important class of potent and selective inhibitors of human cytosolic phospholipase A2 (GIVA cPLA2) combining an aromatic scaffold or a long aliphatic chain with a short aliphatic chain containing a free carboxylic acid. Although highly potent 2-oxoester inhibitors of GIVA cPLA2 have been developed, their rapid degradation in human plasma limits their pharmaceutical utility. In an effort to address this problem, we designed and synthesized two new 2-oxoesters introducing a methyl group either on the α-carbon to the oxoester functionality or on the carbon carrying the ester oxygen. We studied the in vitro plasma stability of both derivatives and their in vitro inhibitory activity on GIVA cPLA2. Both derivatives exhibited higher plasma stability in comparison with the unsubstituted compound and both derivatives inhibited GIVA cPLA2, however to different degrees. The 2-oxoester containing a methyl group on the α-carbon atom to the oxoester functionality exhibits enhancement of the metabolic stability and retains considerable inhibitory potency.

  {MDPI} {AG}, Mar. 2020, Biomolecules, 10(3) (3), 491 - 491, English

  [Refereed]

  Scientific journal


• Screening of subtype-specific activators and inhibitors for diacylglycerol kinase

  Daiki Hayashi, Ryosuke Tsumagari, Ke Liu, Shuji Ueda, Minoru Yamanoue, Fumio Sakane, Yasuhito Shirai

  Lead, Jun. 2019, The Journal of Biochemistry, English

  [Refereed]

  Scientific journal


• Amelioration of diabetic nephropathy by oral administration of d-α-tocopherol and its mechanisms

  Daiki Hayashi, Shuji Ueda, Minoru Yamanoue, Hitoshi Ashida, Yasuhito Shirai

  Diabetic nephropathy (DN) is a diabetic vascular complication, and abnormal protein kinase C (PKC) activation from increased diacylglycerol (DG) production in diabetic hyperglycemia is one of the causes of DN. Diacylglycerol kinase (DGK) converts DG into phosphatidic acid. In other words, DGK can attenuate PKC activity by reducing the amount of DG. Recently, we reported that intraperitoneally administered d-α-tocopherol (vitamin E, αToc) induces an amelioration of DN in vivo through the activation of DGKα and the prevention of podocyte loss. However, the effect of the oral administration of αToc on DN in mice remains unknown. Here, we evaluated the effect of oral administration of αToc on DN and its molecular mechanism using streptozocin-induced diabetic mice. Consequently, the oral administration of αToc significantly ameliorated the symptoms of DN by preventing the loss of podocytes, and it was revealed that the inhibition of PKCactivity was involved in this amelioration.

  Lead, Jan. 2018, Bioscience, Biotechnology, and Biochemistry, 82(1) (1), 65 - 73, English, International magazine

  [Refereed]

  Scientific journal


• Diacylglycerol Kinase alpha is Involved in the Vitamin E-Induced Amelioration of Diabetic Nephropathy in Mice

  Daiki Hayashi, Keiko Yagi, Chihong Song, Shuji Ueda, Minoru Yamanoue, Matthew Topham, Toshinobu Suzaki, Naoaki Saito, Noriaki Emoto, Yasuhito Shirai

  Diabetic nephropathy (DN) is one of vascular complications of diabetes and is caused by abnormal protein kinase C activation as a result of increased diacylglycerol (DG) production in diabetic hyperglycaemia. Diacylglycerol kinase (DGK) converts DG into phosphatidic acid. Therefore, it is expected that the activation of DGK would ameliorate DN. Indeed, it has been reported that vitamin E (VtE) ameliorates DN in rat by activating DGK, and we recently reported that VtE specifically activates DGKα isoform in vitro. However, whether DGKα is involved in the VtE-induced amelioration of DN in vivo remains unknown. Therefore, we investigated the VtE-induced amelioration of DN in wild-type (DGKα+/+) and DGKα–deficient (DGKα−/−) mice in which diabetes was induced by streptozocin. Several symptoms of DN were ameliorated by VtE treatment in the DGKα+/+ mice but not in the DGKα−/− mice. Moreover, transmission electron microscopy of glomeruli and immunofluorescent staining of glomerular epithelial cells (podocytes) indicated that VtE ameliorates podocyte pathology and prevents podocyte loss in the DGKα+/+ mice but not in the DGKα−/− mice. We showed that VtE can ameliorate DN in mice and that DGKα is involved in the VtE-induced amelioration of DN in vivo, suggesting that DGKα is an attractive therapeutic target for DN.

  Lead, Nature Publishing Group, Dec. 2017, Scientific Reports, 7, 2597 - 2597, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Epigallocatechin-3-gallate activates diacylglycerol kinase alpha via a 67 kDa laminin receptor: A possibility of galloylated catechins as functional food to prevent and/or improve diabetic renal dysfunctions

  Daiki Hayashi,Shuji Ueda,Minoru Yamanoue,Naoaki Saito,Hitoshi Ashida,Yasuhito Shirai

  Lead, May 2015, Journal of Functional Foods, English

  [Refereed]

  Scientific journal


• Depression of Type I Diacylglycerol Kinases in Pancreatic β-Cells From Male Mice Results in Impaired Insulin Secretion

  Yukiko Kurohane Kaneko, Yosuke Kobayashi, Keisuke Motoki, Kunihito Nakata, Shoko Miyagawa, Mao Yamamoto, Daiki Hayashi, Yasuhito Shirai, Fumio Sakane, Tomohisa Ishikawa

  Nov. 2013, Endocrinology, English

  [Refereed]

  Scientific journal

• Screening of novel diacylglycerol kinase alpha (DGK alpha) activator to develop drugs improving diabetic nephropathy

  Hayashi Daiki, Liu Ka, Ueda Shuji, Yamanoue Minoru, Sakane Fumio, Shirai Yasuhito

  Jul. 2015, JOURNAL OF PHARMACOLOGICAL SCIENCES, 128(3) (3), S102

  [Refereed]

• Protective Role of Alpha-Tocopherol in Diabetic Nephropathy

  Daiki Hayashi, Yasuhito Shirai

  Contributor, Elsevier, Jun. 2018, ISBN: 9780128120194

• 分子動力学法よる蛋白質-低分子の結合解析を応用した蛋白質の機能解明

  林 大輝

  農芸化学会創立100周年・関西支部創立90周年記念支部大会, Sep. 2024

  [Invited]


• POLYFLUORO KETONES AS POTENT AND SELECTIVE INHIBITORS OF GVIA iPLA2: SYNTHESIS & BIOLOGICAL ACTIVITY

  Batsika S. Charikleia, Bourboula Asimina, Hayashi Daiki, Shinohara Masakazu, Dennis A. Edward, Kokotos George

  23rd Panhellenic Chemistry Conference, Sep. 2024


• Computational analysis on binding structure of limonin to a bitter taste receptor TAS2R38

  Masamune Kashihara, Daiki Hayashi, Shigenori Tanaka, Yoshiko Aihara

  21st IUPAB Congress 2024, Jun. 2024


• GVIA iPLA2の過酸化脂質分解の分子メカニズムとフェロトーシスへの寄与

  北村幸昭, 篠原 正和, 芦田 均, 宇野 知秀, 金丸 研吾, 林 大輝

  第66回日本脂質生化学会, Jun. 2024


• 酸化リン脂質に対する基質特異性に基づくGVIA PLA2特異的阻害剤の改良

  林 大輝, Charikleia S. Batsika, 篠原 正和, Edward A. Dennis, George Kokoto, 宇野知秀, 金丸研吾

  第66回日本脂質生化学会, Jun. 2024


• 膜貫通型リパーゼABHD3の細胞内局在及び膜トポロジーの解明

  山田実佑, 宇野知秀, 金丸研吾, 林大輝

  第70 回日本生化学会近畿支部例会, May 2024


• GVIA iPLA2は過酸化脂質を分解しフェロトーシスを抑制する

  北村 幸昭, 篠原 正和, 芦田 均, 宇野 知秀, 金丸 研吾, 林 大輝

  若手フロンティア研究会2023, Dec. 2023


• ビタミンEの糖尿病性腎症改善効果とそのメカニズム

  林 大輝, 白井康仁

  第96回日本生化学会大会

  Nominated symposium


• Group VIA phospholipase A2のフェロトーシス抑制効果に寄与する基質結合残基の同定

  北村 幸昭, 篠原 正和, 芦田 均, 宇野 知秀, 金丸 研吾, 林 大輝

  第69回日本生化学会近畿支部例会, May 2023

  Poster presentation


• Phospholipase A2の酸化リン脂質に対する基質特異性

  林 大輝, Edward, A. Dennis, 宇野知秀, 金丸研吾

  第69回日本生化学会近畿支部例会, May 2023

  Oral presentation


• Calcium-independent phospholipase A2の酸化リン脂質分解活性のin silico解析

  林 大輝, 北村 幸昭, Edward, A. Dennis, 宇野 知秀, 金丸 研吾

  第76回酸化ストレス学会学術集会

  Oral presentation


• Molecular basis of unique specificity and ATP activation of group VIA calcium-independent phospholipase A2

  Daiki Hayashi, Varnavas D. Mouchlis, Edward A. Dennis

  17th International Conference of Bioactive Lipids in Cancer, Inflammation and Related Diseases, Oct. 2022, English

  Oral presentation

• 細胞膜脂質の恒常性維持を担うホスホリパーゼA2の基質特異性と機能制御機構

  林 大輝

  日本学術振興会, 科学研究費助成事業, 若手研究, 神戸大学, Apr. 2023 - Mar. 2025


• iPLA2の酸化脂質分解の分子基盤解明とその応用

  林 大輝

  公益財団法人 上原記念生命科学財団, 研究奨励金, 神戸大学大学院 農学研究科, Jan. 2023 - Apr. 2024, Principal investigator


• 植物におけるリボソーム蛋白質RPSAの膜受容体としての機能の検証

  林 大輝

  公益財団法人 ひょうご科学技術協会, 学術研究助成, 神戸大学大学院 農学研究科, Mar. 2022 - Apr. 2024, Principal investigator


• 脂質加水分解酵素PLA2の基質特異性の包括的解明

  公益財団法人 上原記念生命科学財団, 海外留学助成, Jan. 2020 - Dec. 2020, Principal investigator


• ＤＧＫαに着目した糖尿病性腎症を改善する機能性食品及び創薬の開発と作用機序の解明

  林 大輝

  日本学術振興会, 科学研究費助成事業, 特別研究員奨励費, 神戸大学, 22 Apr. 2016 - 31 Mar. 2018

  ジアシルグリセロールキナーゼ(DGK)alpha欠損マウスを用いて緑茶カテキンの一種であるEGCgによる糖尿病性腎症(DN)改善効果が実際にDGKalphaを介しているのか否かを検証した。DGKalpha欠損マウスではEGCgによるDN症改善効果が消失する結果が得られ、さらにEGCgによる腎糸球体血管上皮細胞(ポドサイト)の脱落抑制効果もDGKalphaの欠損により消失した。これらのことから、EGCgは実際にDGKalphaの活性化を介し、ポドサイトの脱落を抑制することでDNを改善することが明らかとなった。さらにその詳細なメカニズムを明らかにするため、ヒト培養ポドサイトを用いて実験を行った。ポドサイトをHigh glucose培地で培養すると接着斑の減少が認められた一方で、EGCgを添加した培地ではHigh glucoseによる接着斑の減少が抑制される結果が得られた。このことからEGCgによるDGKalphaの活性化が接着斑の減少を抑制することでポドサイトの脱落を抑制し、DN改善に寄与することが示唆された。また、EGCgよりも吸収が良いメチル化EGCgを用いてそのDN改善能を評価した。メチル化EGCgもDGKalphaの活性化の指標である細胞質膜移行を誘起することを確認し、等量のEGCg及びメチル化EGCgを糖尿病マウスに経口投与しDNの症状を評価した。その結果、メチル化EGCgがより強くDNを改善することが明らかとなった。これらの結果より本研究においてEGCgによるDN改善メカニズムの一部が明らかとなり、さらにメチル化EGCg等の吸収が良く、DGKalphaを活性化する化合物がDNを改善する機能性食品あるいは薬となりうることが示された。